H265: Handle too large Exponential-Golomb coded values

We only allow exp-Golomb coded values to be as large as 32 bit
integers. When packets encode too large a value (invalid content),
clamp the value and report it as malformed with an expert info,
reporting the number of bits consumed (which will probably lead to
a BoundsError later in the packet.)

The case with 32 leading zeroes is a special case because for both
unsigned and signed interpretation there is one non overflowing value.

This is better than using DISSECTOR_ASSERT for invalid packet content.
Avoid left shifting a 32 bit integer by 32, which is undefined.

Use DISSECTOR_ASSERT_FIELD_TYPE at the beginning of the function rather
than using DISSECTOR_ASSERT in the middle, since it's more descriptive
in its error message and clearer code to do it at the start.

Same issue as #17612, commit a7dfe534883ee1f9d9cc84195b64b9a6f1ca9d0d.

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